What These 3 Non-Hurricane
Floods Tell Us About Flood Risk
Flood risk. It’s a coastal problem. It’s a hurricane problem. Right? Wrong.
This spring, thousands of homeowners across the United States faced flood events that had nothing to do with coastal living or tropical storms, illustrating that flood risk is a widespread issue. According to FEMA, 99 percent of all counties in the United States were impacted by flooding between 1996 and 2019. That’s 23 years – less than the life of a typical mortgage.
The problem is that many homeowners don’t realize they’re at risk. Let’s take a look at a few specific flood events from the month of May to spotlight different types of substantial – though often overlooked – flood risk.
1: Dam / Infrastructure Flood Risk (Midland, Michigan)
The area had been saturated with rainfall from storms. Then another five inches fell in only two days, causing the Tittabawassee River to reach a historic high of 34.6 feet. It only needed to rise 28 feet to cause a major flood.
Dam failure is a bigger threat to communities than you may think. Across the country, more than 1,600 dams – in various states of known unsatisfactory repair – pose “high-hazard” fail risk, which means flood risk. Over the past 40 years, about 1,000 dams have failed, killing at least 34 people.
On average, most dams in the United States are 50 to 60 years old, and many are even older, such as the 92-year-old Spencer Dam that failed in northern Nebraska in March 2019. Many of these dams are either in less-than-stellar condition or they simply weren’t built to contain the increased rainfall and flooding associated with climate change.
Live near a dam?
2: Flash Flood Risk (Southwest Virginia)
Multi-day downpours pummeled Southwest Virginia and the western Carolinas in May, dropping over a foot of rain in some areas and triggering widespread flash flooding and mudslides. Southern Appalachia is a high-elevation region, not something homeowners necessarily associate with flooding.
Nevertheless, flood waters rose, trapping people in vehicles and more than two dozen hikers in an area called Devil’s Bathtub, prompting emergency rescue missions in both cases.
The National Severe Storms Laboratory (NSSL) calls flash floods “the most dangerous kind of floods, because they combine the destructive power of a flood with incredible speed.” They can happen within minutes and without warning. According to the NSSL, steep mountainous areas – like the Appalachian region – can produce rapid runoff. Their often rocky, clay-based soils are not suited to absorbing rainwater.
This means that when these areas are hit by prolonged rainfall, a six-inch-deep creek has the potential to grow into a 10-foot-deep river in less than an hour. It can be even more dangerous downstream from the storm, since the cause of the surge may not be immediately apparent.
3: Ice Jam Flood Risk (Southwest Alaska)
This spring, ice jams on the Kuskokwim River in Southwest Alaska caused major flooding, sending water toward the Upper Kalskag power plant and stranding a septuagenarian Napaimute couple, who were eventually rescued by helicopter after escaping their washed-out home.
Ice jam flooding happens when chunks of ice block the flow of a waterway. It’s most likely to occur in the spring, when warmer weather starts to break up and melt ice. Ice chunks can pile up in one area and melt too quickly in another, which means there is suddenly too much water with nowhere safe to go.
Ice jam flooding is not just something that happens in Alaska; it’s been reported in most of the northern 48. Areas of particular concern are north-flowing rivers, such as the Red River of the North in North Dakota. This happens because southern parts of the river can start to melt before colder northern areas.
In February 2019, a widespread deep freeze followed by quick thawing caused several ice jam floods, including near Buffalo, New York; Portland, Michigan; and Houston, Minnesota.
Live near an area prone to ice jams?
New Research Illuminates Coverage in High-Risk Zones
A new report analyzed the National Flood Insurance Program’s (NFIP) and the Furman Center’s flood coverage data to find out which parts of the country have the greatest exposure to flood risk. It focused on homes in so-called 100-year floodplains and found that…
- In the 100 largest US cities in high-risk flood zones, only four out of every 10 homes have an active flood insurance policy.
- Detroit, Cleveland, St. Louis, and four other cities in high-risk flood zones had active policies in less than two out of every 100 homes.
That’s a lot of homes with unmitigated flood risk. Remember, a home located on the 100-year floodplain has a one-percent annual risk of flooding, which equates to a 26 percent chance of flooding at least once over the life of a 30-year mortgage.